Calcium requirements during pregnancy increase significantly to meet the needs of the mother and the developing fetus. This could result in the maternal loss of bone mineral density (up to 3.8% spinal BMD). This loss of BMD may be the combined result of dietary calcium intake falling short of the calcium requirements for pregnancy, and the increased urinary calcium excretion during pregnancy. From our preliminary study of 64 pregnant adolescents, the dietary recall of the previous 24 hours revealed a calculated dietary calcium intake of 978 +/- 532 mg/day, including the 250 mg/day of calcium present in the prenatal supplementation, which is below the RDA for pregnancy. Births from adolescent mothers are known to result in lower birth weight of the individual infants. However, it is not known whether it is associated with altered bone mineral status. The effect of maternal calcium depletion during adolescent pregnancy on the infant BMC has not been studied. The overall aim of this proposal is to determine the effects that the current maternal dietary calcium intake, and calcium supplementation in pregnancy, will have on the infant bone mineral content.